This purpose of this contract is to support the establishment of epidemiologic efforts on HIV infection in the Caribbean and Latin America through the efforts of the Pan American Health Organization. PAHO will establish the financial and administrative mechanisms for NIAID scientists to work unobtrusively in "the Americas" and carry out investigations on HIV infection. Specific planned study areas are: perinatal infections; variability in HIV isolates in different geographic areas and correlation with clinical and epidemiologic resistance factors; co-factor susceptibility studies; and geographic similarities and differences in clinical and epidemiologic presentation in different geographical sites within the region. Although no systematic studies have been conducted in most countries of the Americas, preliminary information seems to indicate that there are important differences (as well as similarities) between countries. The conduct of research studies proposed by this contractor will improve the knowledge and understanding of HIV infection and AIDS. Additionally, these studies may also serve as a stimulus to strengthen local and international efforts to prevent the further spread and consequences of this regional and global public health problem.